Control of gaseous media in manufacturing processes



Jan. 27, 1959 w. K. DONALDSQN ET AL 2, 7

CONTROL OF GASEOUS MEDIA IN MANUFACTURING PROCESSES Filed Sept 8. 1954 3Sheets-Sheet 1 Attorney! Jan. 27, 1959 w. K. DONALDSON ET AL 2,

CONTROL OF GASEOUS MEDIA IN MANUFACTURING PROCESSES Filed Sept. 8. 19543 Sheets-Sheet 2 1 Attorney;

Jan. 27, 1959 W. K. DONALDSON ET AL CONTROL OF GASEOUS MEDIA 'INMANUFACTURING PROCESSES 5 Sheets-Sheet 3 Filed Sept. 8. 1954 .5 M /m,w M

Attorney;

nited States CONTROL OF GASEOUS MEDIA IN IVIANU FACTURING PROCESSESApplication September 8, 1954, Serial No. 454,789

Claims priority, application Great Britain September 18, 1953 1 Claim.(Cl. 73-29) The present invention relates to the control of gaseousmedia in manufacturing processes and in particular to the measurement ofthe proportions of constituents of a gaseous mixture. The invention isespecially applicable for example to the measurement of the proportionsof the constituents of a mixture of air and steam or of air and watervapour or of air and conveniently condensable gases.

The expression measurement when used herein does not necessarily implyan actual quantitative measurement although this may be achieved fairlyaccurately by means of the present invention. other hand imply a gaugingof the proportions of the constituents rather than an actualquantitative measurement in the sense that the invention may be used tocheck whether a mixture is appropriate for carrying out a particularprocess without necessarily ascertaining the actual proportions of theconstituents.

The term constituent when used herein means either a single substance ora mixture of substances all or none of which substances will condenseWithin the range of temperature over which the measurement is carriedout.

The term condensing when used herein means changing the state of oneconstituent from vapour to liquid but does not include deliberatereduction in volume nor the use of chemical absorbent or physicaladsorbent agents.

The invention is applicable to the improvement or control ofmanufacturing operations involving the use of mixtures of gases orvapours or involving the use of gases or vapours liable tocontamination. I

Thus, for example, the invention is applicable to the improvement orcontrol of certain textile printing processes involving the use of steamor to processes for reducing the shrinkability of products containingwool by treatment with a mixture of chlorine and air. Again theinvention is applicable to the improvement or control of a process forproducing a crease-resisting fabric of improved resistance to abrasionin which the fabric bearing resin forming ingredients is passed throughan atmosphere containing superheated steam and in which the best resultsare achieved when the atmosphere is 100% superheated steam or as near100% superheated steam as is possible in practice.

One feature of the present invention is a method of measuring theproportions of the constituents of a gaseous mixture which comprisestaking a sample of the mixture in a sampling space and condensing oneconstituent of the mixture so as to give rise to a pressure change insaid space without allowing said space to fall in temperature to belowthat at which condensation occurs.

Another feature of the invention is a method which comprises admitting asample of the mixture through a sampling connection to a sampling vesseland condensing one constituent thereof so as to give rise to a pressurechange in the vessel but without allowing the tempera- This term may onthe.

area

ture of the vessel and said connection to fall below that r at whichcondensation occurs.

Another feature of the invention is a method which comprises admitting asample of the mixture to a confined sampling space and condensing oneconstituent thereof so as to give rise to a pressure change in saidsampling space by connecting said sampling space to a second confinedspace where the temperature is below the condensing temperature of saidconstituent and whilst maintaining said sampling space at a temperaturenot below the condensing temperature of said constituent. The saidsecond confined space is preferably smaller than the sampling space.

A further feature of the invention is a method which comprisesevacuating a confined space, admitting a sample of the mixture to theconfined space and condensing one constituent thereof so as to. give.rise to a pressure change therein whilst preventing the temperature ofsaid space from falling below that at which condensation occurs.

A further feature of the invention is a method which comprisesevacuating a confined sampling space, admitting a sample of the mixtureto the sampling space and condensing one constituent thereof so as togive rise to a pressure change in said space by connecting said space toa confined condensing space Where the temperature is below thecondensing temperature of said constituent and whilst maintaining saidsampling space at a temperature not below the condensing temperature ofsaid constituent.

A still further feature of the invention consists in a method whichcomprises maintaining a confined sampling space and a confinedcondensing space at different temperatures of which that of the samplingspace is the higher, commonly evacuating said spaces to a standardpressure below atmospheric pressure and then isolating them from oneanother, admitting a sample of themix ture to the sampling space andthen condensing one constituent thereof so as to give rise to a pressurechange in the sampling space by connecting the sampling space to thecondensing space, the temperature of thesampling space being maintainedabove and the temperature of the condensing space being maintained belowthe condensing temperature of said constituent.

Said condensing space is preferably smaller than the sampling space.

A further feature of the invention consists in that the said evacuationis effected by means of a water stream which by heat conduction is alsoused to effect the condensation of said constituent. I

The invention includes the use of the methods herein set forth forcontrolling or maintaining the proportions of a gaseous mixture or forcontrolling a manufacturing operatio-nwhich involves the presence of agaseous mixture.

An apparatus for use in measuring the proportions of the constituents ofa gaseous mixture according to the present invention comprisescondensing means and a sampling vessel which is connectable anddisconnectable to and from a source of a gaseous mixture and to and fromsaid condensing means and a manometer connected or connectable to thesampling vessel to indicate changes of pressure therein. The apparatuspreferably includes valve means adapted automatically to isolate thesampling vessel from the condenser when the sampling vessel is opened tothe source of gaseous mixture and vice versa.

It will usually be advisable or necessary to evacuate the apparatus downto a relatively low pressure before admission of a sample of the gaseousmixture thereto and thus a further feature of the invention consists inthe provision of an evacuating means, such as a vacuum pump, connectablewith the sampling vessel.

The apparatus is preferably provided with a valve means controlling theconnection of the sampling vessel with the condensing means and with theevacuating means and with the source of the gaseous mixture which isoperable by a common control such that in a first position of thecontrol the sampling vessel is connected to the condensing means and tothe evacuating means and isolated from said source and in a secondposition the sampling vessel is connected to the source and iso latedfrom the condensing means and evacuating means whilst in a thirdposition tie sampling vessel is connected to the condensing means butisolated from the evacuating means and from said source.

The manometer is preferably arranged so that it can be connected to thesampling vessel by a valve means which also connects the sampling vesselwith the condensing means. Thus the manometer 'may be connected to thesampling vessel through the condensing means.

An important feature of the invention consists in maintaining-thesampling vessel and its connections to the source of gaseous mixture ata temperature above that at which condensation occurs. This may beachieved either by positioning the sampling vessel and its connectionsto the source of gaseous mixture actually within the source of thegaseous mixture, e. g. within an'oven, conditioner or the like or it maybe achieved by suitably heating the sampling vessel and its connectionsto the source of the gaseous mixture so as to keep them at atemperatureabove that at which condensation occurs; Thus the sampling vessel andits connections to the source of' gaseous mixture may be suitablyenclosed and/or lagged, for' example by glass wool, and/or provided witha suitable heating means such as an electrical heating means. a

If the manometer is permanently connected to the sampling vessel thensimilar arrangements must be made to maintain the temperature of themanometer and its connection to the sampling vessel above that at whichcondensation occurs. If however, the manometer can be isolated from thesampling'vessel then this safeguard is not necessary.

A preferred form of evacuating means consists of a jetpump operated bywater or other liquid and comprising a body having a passagether'ethrough which abruptly enlarges in cross sectional area ordiameter and having a suction duct'or opening leading into the enlargedpassage adjacent tothe place at which the crosssection or diameter isabruptly enlarged; In other words the. jet pump consists of a bodyhaving 'a passage with a step at which. the passage enlarged and with asuction duct or'opening entering the enlarged passage close to the step.Thus the jet pump can be of simple and inexpensive construction and'canconsist of'a single block of metal orother material suitably drilled.

The body of the jet pump may be cooledby the flow of liquid therethroughand may be formed so as to serve also as the condensing means. Thus thebody of the jet pump may be formed of metal and may have an opening orpassage therein which is connectable to the samplingvessel and adaptedtoserve as a condensing means.

A preferred form of valve arrangement for use in the apparatus of thepresent invention is one in which a valve element of substantiallyconstant cross section over at least a portion of its length, andpreferably of rodlike; form, is longitudinally displaceable within aduct or passage and is surrounded by a resilient annular seal lyingbetween the duct orpassage and-the valve element which latter haslongitudinally spaced interconnected ports or openings therein at leastone of which, by longitudinal displacement of the valve elementrelatively to the duct and seal, maylie on oneorother side of theseal tocloseor open the valve.

In the preferred form of construction of the invert-- tion a singlevalve rod is formed with three such valve elements to controlrespectively the connection of the sampling vessel to the source of thegaseous mixture,

the connection of the sampling'vessel to theeendensing means and theconnection of the evacuating means to the condensing means. Said rod maybe formed with a further valve element through which the apparatus canbe connected to the atmosphere whilst remaining isolated from the sourceof the gaseous mixture.

The invention is further described with reference to the accompanyingdrawings in which:

Fig. 1 is a diagrammatic view of an apparatus accord ing to the presentinvention in which the sampling vessel is not located within the sourceof the gaseous mx ture.

Fig. 2 is a longitudinal sectional side view of a preferred form ofapparatus accordingto the invention.

Fig. 3 is a front view corresponding to Fig. 2.

Figs. 4, 5, 6 and 7 are diagrammatic views illustrating the valve meansof Fig. 2 in different positions.

In the arrangement diagrammatically shown in Fig. l a sampling vessel 1can be connected through a two-way valve 3 either to a pipe 4 leadinginto a source 2 of gaseous mixture, e. g. an oven, or to a'pipe' 5 whichpasses through a condenser 6-. The pipe 5 continues of the samplingvessel.

through the condenser to a valve 7 which either seals the end of thepipe 5 or connects it to an evacuating means 8 such as :an extractionpump. A manometer 9 is connected to the pipe 5 on that side of thecondenser remote from the sampling vessel.

It isoften desirable that the volume of the sampling vessel be verysmall compared with that 'ofthe source of the mixture so that samplingshall have little effect on the source. It is also desirable that thevolume of the condensing system should be small compared with thatLikewise it'is desirable to choose a manometer of low internal volume.

It is desirable that the sampling vessel and its connections to thesource of the gaseous mixture should be maintained substantially at thetemperature of the source of the gaseous mixture or at least notbelow-the condensingtemperature of the condensable constituent of thegaseous mixture. For this purpose the sampling vessel 1, valve 3 and thepipe 4 might have been arranged within the source 2 of the gaseousmixture, but that isnot' always a convenient arrangementand'thusirrFi'gi 1" thesampling vessel, the valve 3 and portion of thepipe 4 are enclosed by a housing or casing'lll which is suitably laggedand heated in order to keepthe temperature of the sampling vessel 1,valve 3 and pipe 4 substantially'equal tothatof the source of thegaseous" mixture.

The apparatus illustrated in Figs; 2' and 3 includes a sampling vessel 1which can be connected at' its lefthand end to a sourceof'the' gaseousmixture through a tubular sampling connection 4 and it is connected atits righthand end' by a tubular connection Swit'h a metal block 12through which is'formed a passage 13'coaxial with the tubular connection5""and with openings or ducts 24, 25 in the ends26; 27 of thesamplingjivessel 1. The metal block is formed with passagesthereinconstituting a jet pump generally indicated bythe' reference numeralSand comprising a passage 14 connectedtoa water supply through anexternal pipe connection 15 and which narrows downwardly at 16 and isthen abruptlyv increased in diameter or cross-sectional area by means ofa step 17. A suction duct or opening 18 enters the passage 14 at or justbelow the step 17 where it increases in diameter. The suction duct 18 isconnected through a non-return valve 19 to anevacuatingopehingLZfl-inthe passage'13; The jet pump S-disch-argesthrough. an external pipe conmotion 21 The block- 12-.has a passage'ZZ-thei'ein which opens into the passage 13'-and is connected through anexternal pipe connection 23"with*a manometer 9.

Since the block 12 is cooled by the water flowing through the jet'pump 8formed therein and sin'ce'the passage 13 therein is connected by thetubular'conneca condenser 'for ,the'sampling vessel.-

' assumetion with th c sarnpling'vessel l,the bio ch12 serves as A valverod 11 extends through the passage 13 of the block'12 and through theopenings or ducts'f24, in'the ends 26, 27 of the'sampling-vessel 1.; Therod 11 embodies three valve elements which 'are'r'eferenc'ed 311,317

and 7 of which the valve elements 3a and 3b perform the function of thevalve'3 shown in Fig. l and the valve element 7 performs the function ofthe valve 7 shown in Fig.1., Thevalve elements 3b and 7- havelongitudinally spaced interconnected ports 28, 29 whilst the valve ele-.

ment 3a has a port 30 whieh is longitudinally connected to the lefthandend of the rod 11. -A further valve. elemeat 31 is formed in therightli-and end of the rod .11.

'The valve elements 3a and 3b aremovable relatively to resilient annularseals 32, 33 housed in annular grooves form-ed inthe ducts or openings24, 25 in the end walls of the sampling vessel '1. The valve elements 7and 31 are movable relatively to resilient annularseals 34, 35

' 'housed in, annular grooves formed in the passage 13 in g the block 12and located on opposite sides of the evacuating opening 20.

The valve rod 11 is longitudinally displaced by means -of a cam 36having a cam groove 37 formed therein which is engaged by a pin 38 atthe righthand end of the valve rod '11. The cam 36 is connected-througha stub shaft 40 with a control knob 41, the stub-shaft 40 being Themetal block 12 has a bore 46 therein communi- I eating with the passage22 which is connected to the manometer 9. The bore 46 receives a plunger47 which is sealed by a gland 48.. By endwise displacement of theplunger 47 the total volume of the condenser and its connections to themanometer and to the sampling vessel can be adjusted in relation to thevolume of the sampling vvessel. Thus adjustmentis useful in thecalibration of the manometer 9.

In using the apparatus of Fig. 2 the first step is to isolate thesampling vessel from the tubular connection 4, i. e. from the source ofthe gaseous mixture, whilst at the same time connecting it with the jetpump 8 and with the condensing system of the metal block 12 and which34': and '7 are closed. and. the valve element 315 isoperiwith itslongitudinally interconnected ports 28, 29 lying on opposite sides ofthe resilient annular seal 33. 'The proportions of the gaseous mixturewill indicated by the manometer 9.

At the end of a series of tests the internal pressure within theapparatus can be brought up to atmosphere pressure by moving the valverod 11 to the position shown in Fig. 7 in which the atmospheric valveelement 31 and'the valve elements 3b and 7 are open and the valveelement 3a closed.

then be i The cam groove 37 in the cam 36 is formed so that the valverod 11 can be moved successivelyinto the positio'nsshown in Figs. 4, 5,6' and-7 by unidirectional movement of the control knob 41.

The advantage of keeping the sampling vessel and its connections at a.temperature not below the condensation temperature enables samples ofthe gaseous mixture to be tested as frequently as may be desirable andwithout any time interval which would otherwise be required forreheatingthe sampling vessel after condensation has taken place.

may be regarded as the passage 22 and that part of the passage 13 lyingto the left of the annular sealing ring 34. This can be achieved byrotating the knob 41 to brlng the valve rod 11 into the position shownin Fig. 4 when the valve elements 312 and 7 are-open and the valveelement 3a is closed. With the valve rod 11 in the position shown inFig. 4 the sampling vessel 1 and the condensing system will beevacuated. 1

The second step is to disconnect the sampling vessel 1 from the pump 8and from the condensing'system and to connect it with the source of thegaseous mixture through the tubular connection 4. This can be achievedby rotating the control knob 41 to bring the valve rod 11 into aposition shown in Fig. 5 when'the valve ele-' ment 3a is open and thevalve elements 3b and 7 are closed, since both of their longitudinallyinterconnected ports lie to one side of the resilient annular seals 33,

34. With the valve rod 11 in the position shown in Fig. 5 a sample ofthe gaseous mixture will be drawn into the sampling vessel 1.

The third step is to disconnect the sampling vessel 1 from the source ofthe gaseous mixture and to connect The apparatus of Figs. 2 and 3 as sofar described is suitable for use when the sampling vessel and itstubular connection 4 are to be inserted into thesource ofthe gaseousmixture. If, however, the sampling vessel 1 and the connection 4 are notto be inserted into the source of the gaseous mixture then they will beprovided withan enclosure and/or lagging diagrammatically indicated bythe broken lines 50 and with an electrical heating means such as aspiral element diagrammatically indicated at 51 wound around theenclosure 50, lagged and controlled in part by a thermostatic element52.

Preferably the manometer 9 is not one which measures pressures on theabsolute scale but is of the type which indicates diiferences fromatmospheric pressure i. e. an

open manometer. If it is a Bourden gauge the usual unsealed case issuitable.

It is preferable to evacuate the sampling vessel 1 by means of the jetpump 8 to a convenient standard vacuum figure e. g. 27 inches of mercurybelow atmospheric pressure.

The use of a standard vacuum figure of the order of 27 inches yields theadvantage of rendering the calibration of the manometer or vacuum gaugevirtually independent of variations of atmospheric pressure.

The manometer is preferably calibrated, for steam/ air or othermixtures, on the assumptions of virtually constant volumes of samplingand condensing systems, virtually constant sampling temperature andcondensing temperature and the presence in the condensing system of afree liquid surface of the condensable constituent.

For example when measuring the proportions of the constituents of amixture of steam and air, using a standard vacuum figure and knowing thevolumes of the sampling system (i. e. of the sampling vessel 1 up to thevalve element 3b) and of the condensing system lying between the valveelements 311 and 7 and including the manometer 9 and knowing thetemperature of the sampling system and of the condensing system it ispossible to calculate the reading of the gauge after a sample of aircontaining no steam has been admitted to the sampling vessel and thesampling vessel has been connected to the condensing system. When asample containing of steam is so condensed after admission to thesampling vessel, then if, as is preferred, the temperatures of bothsampling and condensing systems remain constant then the pressure willremain constant at the standard vacuum figure, e. g. 27 inches.

Having calculated as indicated above the gauge reading which correspondsto 0% steam, the graduation of the scale between the readingscorresponding to 0% and 100% steam can be made since the scale betweenthese points is linear.

The manometer may be associated with any suitable reqqrd devic t p o d nt cpe m nen ord Qt may be a ted to p form a c tro in ope at on. in

apparatus r in ur ngzthe p pow j ionfi of the constituents of a mixtureof steam and air including a sampling vessel, a, manometer forindicating changes of pressure in the sampling vessel, means formaintaining the sampling vessel at a temperature above the conden sationtemperature of the steam, a jet pump comprising. i

a ody defining a passa et e e r u hich' pasw e,

abruptly enlarges in crossesectionalarea or diameter, a w m du ommun a ih e enl r d P s adjacent to the position at which lthe enlargementoccurs,

said body defining a further passage enabling it to -.serve s condensingmeans, and Y k x meepifm 9 1Ptil h sampling vesseLto the s ource ofsaid', mixture, and to said condensing means, and further valve meanstor connecting said jet pump to said'sarnpling' vessel and said de inmeaasr t 'n'rereii es Cited in the file of'tbis pa e t UNITED. STATESPATENTS Lacy July 9, 19.13

1,272,059 I 1,880,720 Blackwood et'al. Oct. 4, 1932' 2,212,681 DunnAug.27,v1940" 2,287,101 Horvitz June23, 1942. 2,643,541" McCreary' June30, 194E: 2,721,578

